Ternary semiconductors are potential candidate for optoelectronic and photoelectrochemical (direct solar water splitting) applications owing to their tunable composition-dependent properties. Solar water splitting requires the material to have a band gap between 1.7 and 2.2 eV and the band edges to straddle H2/O2 redox potentials. Gallium nitride (GaN), a wide, direct-band-gap semiconductor, has been shown to be stable under visible photolysis and has the right band edge energetics. Tandem cells based on III-V materials have been shown to have very high efficiency for spontaneous photoelectrochemical (PEC) water splitting (≈12%), but their applicability as single-gap cells for direct photoelectrochemical water splitting has been limited by the unfavorable band energetics.
The successful development of photocatalysts, which work under visible-light irradiation to efficiently utilize solar energy, has remained elusive. This document relates to antimony substituted gallium nitride composition of matter, an antimony substituted gallium nitride semiconductor electrode and to a photoelectrochemical cell including such an electrode.